Media stream delivery is typically accomplished using a media source (e.g., a video camera or stream server) that provides a media stream (e.g., a video stream) over an intervening network to a client device, e.g., client viewing software that operates on a Personal Computer (PC). In the case of video stream technology, a video access component (usually a video stream server) is typically present between a video source and a client device, or is the sole video stream source for recorded video content. The video access component delivers the video stream to the client device. In the case of video stream delivery, it is possible that the video camera and stream server components may be one device. It is also possible that the video access component may deliver stored/recorded video content without a camera device.
Current media streaming technology uses real time protocols, such as Real-time Transport Protocol (RTP) to transport data at a real time rate to a client mechanism that presents the media to a user at the real time rate. In order to present one minute's worth of media to a client, one minute's worth of data is transported in one minute using one “unit” of bandwidth (i.e., a “unit” is usually some corresponding bit rate value). By definition, the speed of this process is 1× (1 minute of media/1 minute to deliver). In some industries, such as the security and surveillance industries, their exists the need to review media streams faster than real time. Using conventional technology, additional bandwidth “units” are required to review more than one minute of data in one minute. For example, to review four minutes of data in only one minute, four minute's worth of data is sent in one minute using four “units” of bandwidth. This process is known as ‘4×’ (4 minutes of media/1 minute to deliver). Thus, for conventional media streaming technology, the “cost” of extra speed is additional bandwidth. Furthermore, using conventional technology a problem is soon encountered where enough bandwidth does not reasonably exist to transmit a given media segment at faster and faster speeds. The result is that an undesirably large amount of time is often required to review media of any significant duration when using conventional media streaming technology.
Current security industry practice is to deliver a MPEG-4 (Moving Pictures Expert Group, “MPEG”) stream over an RTP transport. A 4-SIF (source input format, “SIF”) image (usually 640H×480V) stream delivered at 30 frames per second (fps) typically requires 2-5 MBits per second (Mbps). RTP offers a speed parameter as part of the “PLAY” command that instructs a compliant server to deliver the streamed content as some rate faster. For example, if the “PLAY” parameter is issued with a parameter of “speed=4.0”, the aforementioned 2-5 Mbps stream is now delivered four times faster (4×), requiring 8-20 Mbps. While this has the desired effect of getting the video to the client system faster, it also has the side effect of taking up more bandwidth as described above. Furthermore, even with four times increase in video stream delivery speed, 24 hours of video still requires 6 hours to download and view. Although this time may be reduced by requesting even faster playback rates, increasing the playback speed increases the required bandwidth usage of the stream. Eventually such increases in bandwidth become a limiting factor so that further increases in the speed of content delivery to the client are not possible, or feasible.
A further practical example of the shortcomings of current media stream delivery technology is to consider bandwidth requirements to deliver and review a high resolution full motion video stream at a speed of 60×. Using an MPEG-4 based codec, such a high resolution full motion video stream would nominally require 5 Mbps bandwidth for delivery. If this video stream were to be transported at a rate of 60×, the bandwidth required would be 5 Mbps*60×=300 Mbps. Such speeds are not possible on standard 100 Mbps networks, nor are they reasonable even for Gigabit networks which usually carry other forms of data traffic. To illustrate further, if useable bandwidth on a hypothetical network were limited to 10 Mbps of bandwidth to be utilized for moving this media stream, a maximum speed of 2× (10 Mbps/5 Mbps=2×) could be achieved. At this delivery rate, 30 minutes would be required to review one hour of this media stream, and roughly 12 hours would be required to review one day of this media stream. In a practical situation (such as upon occurrence of a crime or other significant event) where 24 hours of media from 4 different sources must be reviewed, it would take approximately 48 hours, or more than a standard work week, to accomplish this task.